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1 /* | |
2 ****************************************************************************** | |
3 * | |
4 * Copyright (C) 2009-2010, International Business Machines | |
5 * Corporation and others. All Rights Reserved. | |
6 * | |
7 ****************************************************************************** | |
8 * | |
9 * FILE NAME : icuplug.h | |
10 * | |
11 * Date Name Description | |
12 * 10/29/2009 sl New. | |
13 ****************************************************************************** | |
14 */ | |
15 | |
16 /** | |
17 * \file | |
18 * \brief C API: ICU Plugin API | |
19 * | |
20 * <h2>C API: ICU Plugin API</h2> | |
21 * | |
22 * <p>C API allowing run-time loadable modules that extend or modify ICU functio
nality.</p> | |
23 * | |
24 * <h3>Loading and Configuration</h3> | |
25 * | |
26 * <p>At ICU startup time, the environment variable "ICU_PLUGINS" will be | |
27 * queried for a directory name. If it is not set, the preprocessor symbol | |
28 * "DEFAULT_ICU_PLUGINS" will be checked for a default value.</p> | |
29 * | |
30 * <p>Within the above-named directory, the file "icuplugins##.txt" will be | |
31 * opened, if present, where ## is the major+minor number of the currently | |
32 * running ICU (such as, 44 for ICU 4.4, thus icuplugins44.txt)</p> | |
33 * | |
34 * <p>The configuration file has this format:</p> | |
35 * | |
36 * <ul> | |
37 * <li>Hash (#) begins a comment line</li> | |
38 * | |
39 * <li>Non-comment lines have two or three components: | |
40 * LIBRARYNAME ENTRYPOINT [ CONFIGURATION .. ]</li> | |
41 * | |
42 * <li>Tabs or spaces separate the three items.</li> | |
43 * | |
44 * <li>LIBRARYNAME is the name of a shared library, either a short name if | |
45 * it is on the loader path, or a full pathname.</li> | |
46 * | |
47 * <li>ENTRYPOINT is the short (undecorated) symbol name of the plugin's | |
48 * entrypoint, as above.</li> | |
49 * | |
50 * <li>CONFIGURATION is the entire rest of the line . It's passed as-is to | |
51 * the plugin.</li> | |
52 * </ul> | |
53 * | |
54 * <p>An example configuration file is, in its entirety:</p> | |
55 * | |
56 * \code | |
57 * # this is icuplugins44.txt | |
58 * testplug.dll myPlugin hello=world | |
59 * \endcode | |
60 * <p>Plugins are categorized as "high" or "low" level. Low level are those | |
61 * which must be run BEFORE high level plugins, and before any operations | |
62 * which cause ICU to be 'initialized'. If a plugin is low level but | |
63 * causes ICU to allocate memory or become initialized, that plugin is said | |
64 * to cause a 'level change'. </p> | |
65 * | |
66 * <p>At load time, ICU first queries all plugins to determine their level, | |
67 * then loads all 'low' plugins first, and then loads all 'high' plugins. | |
68 * Plugins are otherwise loaded in the order listed in the configuration file.</
p> | |
69 * | |
70 * <h3>Implementing a Plugin</h3> | |
71 * \code | |
72 * U_CAPI UPlugTokenReturn U_EXPORT2 | |
73 * myPlugin (UPlugData *plug, UPlugReason reason, UErrorCode *status) { | |
74 * if(reason==UPLUG_REASON_QUERY) { | |
75 * uplug_setPlugName(plug, "Simple Plugin"); | |
76 * uplug_setPlugLevel(plug, UPLUG_LEVEL_HIGH); | |
77 * } else if(reason==UPLUG_REASON_LOAD) { | |
78 * ... Set up some ICU things here.... | |
79 * } else if(reason==UPLUG_REASON_UNLOAD) { | |
80 * ... unload, clean up ... | |
81 * } | |
82 * return UPLUG_TOKEN; | |
83 * } | |
84 * \endcode | |
85 * | |
86 * <p>The UPlugData* is an opaque pointer to the plugin-specific data, and is | |
87 * used in all other API calls.</p> | |
88 * | |
89 * <p>The API contract is:</p> | |
90 * <ol><li>The plugin MUST always return UPLUG_TOKEN as a return value- to | |
91 * indicate that it is a valid plugin.</li> | |
92 * | |
93 * <li>When the 'reason' parameter is set to UPLUG_REASON_QUERY, the | |
94 * plugin MUST call uplug_setPlugLevel() to indicate whether it is a high | |
95 * level or low level plugin.</li> | |
96 * | |
97 * <li>When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin | |
98 * SHOULD call uplug_setPlugName to indicate a human readable plugin name.</li><
/ol> | |
99 * | |
100 * | |
101 * \internal ICU 4.4 Technology Preview | |
102 */ | |
103 | |
104 | |
105 #ifndef ICUPLUG_H | |
106 #define ICUPLUG_H | |
107 | |
108 #include "unicode/utypes.h" | |
109 | |
110 | |
111 /* === Basic types === */ | |
112 | |
113 /** | |
114 * @{ | |
115 * Opaque structure passed to/from a plugin. | |
116 * use the APIs to access it. | |
117 * @internal ICU 4.4 Technology Preview | |
118 */ | |
119 | |
120 struct UPlugData; | |
121 typedef struct UPlugData UPlugData; | |
122 | |
123 /** @} */ | |
124 | |
125 /** | |
126 * Random Token to identify a valid ICU plugin. Plugins must return this | |
127 * from the entrypoint. | |
128 * @internal ICU 4.4 Technology Preview | |
129 */ | |
130 #define UPLUG_TOKEN 0x54762486 | |
131 | |
132 /** | |
133 * Max width of names, symbols, and configuration strings | |
134 * @internal ICU 4.4 Technology Preview | |
135 */ | |
136 #define UPLUG_NAME_MAX 100 | |
137 | |
138 | |
139 /** | |
140 * Return value from a plugin entrypoint. | |
141 * Must always be set to UPLUG_TOKEN | |
142 * @see UPLUG_TOKEN | |
143 * @internal ICU 4.4 Technology Preview | |
144 */ | |
145 typedef uint32_t UPlugTokenReturn; | |
146 | |
147 /** | |
148 * Reason code for the entrypoint's call | |
149 * @internal ICU 4.4 Technology Preview | |
150 */ | |
151 typedef enum { | |
152 UPLUG_REASON_QUERY = 0, /**< The plugin is being queried for info. **/ | |
153 UPLUG_REASON_LOAD = 1, /**< The plugin is being loaded. **/ | |
154 UPLUG_REASON_UNLOAD = 2, /**< The plugin is being unloaded. **/ | |
155 UPLUG_REASON_COUNT /**< count of known reasons **/ | |
156 } UPlugReason; | |
157 | |
158 | |
159 /** | |
160 * Level of plugin loading | |
161 * INITIAL: UNKNOWN | |
162 * QUERY: INVALID -> { LOW | HIGH } | |
163 * ERR -> INVALID | |
164 * @internal ICU 4.4 Technology Preview | |
165 */ | |
166 typedef enum { | |
167 UPLUG_LEVEL_INVALID = 0, /**< The plugin is invalid, hasn't called uplug
_setLevel, or can't load. **/ | |
168 UPLUG_LEVEL_UNKNOWN = 1, /**< The plugin is waiting to be installed. **/ | |
169 UPLUG_LEVEL_LOW = 2, /**< The plugin must be called before u_init co
mpletes **/ | |
170 UPLUG_LEVEL_HIGH = 3, /**< The plugin can run at any time. **/ | |
171 UPLUG_LEVEL_COUNT /**< count of known reasons **/ | |
172 } UPlugLevel; | |
173 | |
174 /** | |
175 * Entrypoint for an ICU plugin. | |
176 * @param plug the UPlugData handle. | |
177 * @param status the plugin's extended status code. | |
178 * @return A valid plugin must return UPLUG_TOKEN | |
179 * @internal ICU 4.4 Technology Preview | |
180 */ | |
181 typedef UPlugTokenReturn (U_EXPORT2 UPlugEntrypoint) ( | |
182 UPlugData *plug, | |
183 UPlugReason reason, | |
184 UErrorCode *status); | |
185 | |
186 /* === Needed for Implementing === */ | |
187 | |
188 /** | |
189 * Request that this plugin not be unloaded at cleanup time. | |
190 * This is appropriate for plugins which cannot be cleaned up. | |
191 * @see u_cleanup() | |
192 * @param plug plugin | |
193 * @param dontUnload set true if this plugin can't be unloaded | |
194 * @internal ICU 4.4 Technology Preview | |
195 */ | |
196 U_CAPI void U_EXPORT2 | |
197 uplug_setPlugNoUnload(UPlugData *plug, UBool dontUnload); | |
198 | |
199 /** | |
200 * Set the level of this plugin. | |
201 * @param plug plugin data handle | |
202 * @param level the level of this plugin | |
203 * @internal ICU 4.4 Technology Preview | |
204 */ | |
205 U_CAPI void U_EXPORT2 | |
206 uplug_setPlugLevel(UPlugData *plug, UPlugLevel level); | |
207 | |
208 /** | |
209 * Get the level of this plugin. | |
210 * @param plug plugin data handle | |
211 * @return the level of this plugin | |
212 * @internal ICU 4.4 Technology Preview | |
213 */ | |
214 U_CAPI UPlugLevel U_EXPORT2 | |
215 uplug_getPlugLevel(UPlugData *plug); | |
216 | |
217 /** | |
218 * Get the lowest level of plug which can currently load. | |
219 * For example, if UPLUG_LEVEL_LOW is returned, then low level plugins may load | |
220 * if UPLUG_LEVEL_HIGH is returned, then only high level plugins may load. | |
221 * @return the lowest level of plug which can currently load | |
222 * @internal ICU 4.4 Technology Preview | |
223 */ | |
224 U_CAPI UPlugLevel U_EXPORT2 | |
225 uplug_getCurrentLevel(void); | |
226 | |
227 | |
228 /** | |
229 * Get plug load status | |
230 * @return The error code of this plugin's load attempt. | |
231 * @internal ICU 4.4 Technology Preview | |
232 */ | |
233 U_CAPI UErrorCode U_EXPORT2 | |
234 uplug_getPlugLoadStatus(UPlugData *plug); | |
235 | |
236 /** | |
237 * Set the human-readable name of this plugin. | |
238 * @param plug plugin data handle | |
239 * @param name the name of this plugin. The first UPLUG_NAME_MAX characters will
i be copied into a new buffer. | |
240 * @internal ICU 4.4 Technology Preview | |
241 */ | |
242 U_CAPI void U_EXPORT2 | |
243 uplug_setPlugName(UPlugData *plug, const char *name); | |
244 | |
245 /** | |
246 * Get the human-readable name of this plugin. | |
247 * @param plug plugin data handle | |
248 * @return the name of this plugin | |
249 * @internal ICU 4.4 Technology Preview | |
250 */ | |
251 U_CAPI const char * U_EXPORT2 | |
252 uplug_getPlugName(UPlugData *plug); | |
253 | |
254 /** | |
255 * Return the symbol name for this plugin, if known. | |
256 * @param plug plugin data handle | |
257 * @return the symbol name, or NULL | |
258 * @internal ICU 4.4 Technology Preview | |
259 */ | |
260 U_CAPI const char * U_EXPORT2 | |
261 uplug_getSymbolName(UPlugData *plug); | |
262 | |
263 /** | |
264 * Return the library name for this plugin, if known. | |
265 * @param plug plugin data handle | |
266 * @param status error code | |
267 * @return the library name, or NULL | |
268 * @internal ICU 4.4 Technology Preview | |
269 */ | |
270 U_CAPI const char * U_EXPORT2 | |
271 uplug_getLibraryName(UPlugData *plug, UErrorCode *status); | |
272 | |
273 /** | |
274 * Return the library used for this plugin, if known. | |
275 * Plugins could use this to load data out of their | |
276 * @param plug plugin data handle | |
277 * @return the library, or NULL | |
278 * @internal ICU 4.4 Technology Preview | |
279 */ | |
280 U_CAPI void * U_EXPORT2 | |
281 uplug_getLibrary(UPlugData *plug); | |
282 | |
283 /** | |
284 * Return the plugin-specific context data. | |
285 * @param plug plugin data handle | |
286 * @return the context, or NULL if not set | |
287 * @internal ICU 4.4 Technology Preview | |
288 */ | |
289 U_CAPI void * U_EXPORT2 | |
290 uplug_getContext(UPlugData *plug); | |
291 | |
292 /** | |
293 * Set the plugin-specific context data. | |
294 * @param plug plugin data handle | |
295 * @param context new context to set | |
296 * @internal ICU 4.4 Technology Preview | |
297 */ | |
298 U_CAPI void U_EXPORT2 | |
299 uplug_setContext(UPlugData *plug, void *context); | |
300 | |
301 | |
302 /** | |
303 * Get the configuration string, if available. | |
304 * The string is in the platform default codepage. | |
305 * @param plug plugin data handle | |
306 * @return configuration string, or else null. | |
307 * @internal ICU 4.4 Technology Preview | |
308 */ | |
309 U_CAPI const char * U_EXPORT2 | |
310 uplug_getConfiguration(UPlugData *plug); | |
311 | |
312 /** | |
313 * Return all currently installed plugins, from newest to oldest | |
314 * Usage Example: | |
315 * \code | |
316 * UPlugData *plug = NULL; | |
317 * while(plug=uplug_nextPlug(plug)) { | |
318 * ... do something with 'plug' ... | |
319 * } | |
320 * \endcode | |
321 * Not thread safe- do not call while plugs are added or removed. | |
322 * @param prior pass in 'NULL' to get the first (most recent) plug, | |
323 * otherwise pass the value returned on a prior call to uplug_nextPlug | |
324 * @return the next oldest plugin, or NULL if no more. | |
325 * @internal ICU 4.4 Technology Preview | |
326 */ | |
327 U_CAPI UPlugData* U_EXPORT2 | |
328 uplug_nextPlug(UPlugData *prior); | |
329 | |
330 /** | |
331 * Inject a plugin as if it were loaded from a library. | |
332 * This is useful for testing plugins. | |
333 * Note that it will have a 'NULL' library pointer associated | |
334 * with it, and therefore no llibrary will be closed at cleanup time. | |
335 * Low level plugins may not be able to load, as ordering can't be enforced. | |
336 * @param entrypoint entrypoint to install | |
337 * @param config user specified configuration string, if available, or NULL. | |
338 * @param status error result | |
339 * @return the new UPlugData associated with this plugin, or NULL if error. | |
340 * @internal ICU 4.4 Technology Preview | |
341 */ | |
342 U_CAPI UPlugData* U_EXPORT2 | |
343 uplug_loadPlugFromEntrypoint(UPlugEntrypoint *entrypoint, const char *config, UE
rrorCode *status); | |
344 | |
345 | |
346 /** | |
347 * Inject a plugin from a library, as if the information came from a config file
. | |
348 * Low level plugins may not be able to load, and ordering can't be enforced. | |
349 * @param libName DLL name to load | |
350 * @param sym symbol of plugin (UPlugEntrypoint function) | |
351 * @param config configuration string, or NULL | |
352 * @param status error result | |
353 * @return the new UPlugData associated with this plugin, or NULL if error. | |
354 * @internal ICU 4.4 Technology Preview | |
355 */ | |
356 U_CAPI UPlugData* U_EXPORT2 | |
357 uplug_loadPlugFromLibrary(const char *libName, const char *sym, const char *conf
ig, UErrorCode *status); | |
358 | |
359 /** | |
360 * Remove a plugin. | |
361 * Will request the plugin to be unloaded, and close the library if needed | |
362 * @param plug plugin handle to close | |
363 * @param status error result | |
364 * @internal ICU 4.4 Technology Preview | |
365 */ | |
366 U_CAPI void U_EXPORT2 | |
367 uplug_removePlug(UPlugData *plug, UErrorCode *status); | |
368 | |
369 | |
370 #endif | |
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